Used the search engine on what ISIS crank arm extractor to get and was just wondering how they actually work. 
the outer sleeve screw in to a thread inside the crank, you then do up the middle pin, this pushes against the end of the axle and so drage the crank off the spline. Two important things: take out the bolt before you do it, make sure you;re using an ISIS product for ISIS cranks, a ST extractor is smaller and can cause serious damage.
The Park Tools extractor is the be all and end all of extractors, but you cqan get smaller and cheaper ones that rely on you using a wrench on them rather than having an integrated handle.
Do you want to keep the pedal on ?
I have a nice Pedro puller that has an adapter for square or splined. It has a handle, that means I must remove the pedal to use it.
If you want to pull a crank, without changing pedals, a puller without a handle is the way to go.
They work like a gear-puller. The outer shell fastens into the crank arm and then you tighten the center bolt. As you do, the center bolt pushes on the axle while the outer shell pulls on the crank arm, separating the two.
I would stick with the Park Tool extractors. It is critical that the extractor threads fit tightly in the crank, especially with aluminum cranks, or else you might pull the extractor out of the crank, destroying the threads in the crank in the process. The Park Tool extractors have very high quality threads. For Unicycles, I prefer the CWP-6 (requires a wrench) over the CCP-2(square-taper) or CCP-4(ISIS) because I don’t need to pull the pedals first. An extractor for ISIS or Shimano splined cranks has a larger “tip” where it contacts the axle; it is important to use the right tip for the type cranks you have. The small tip will go into and destroy the threads on an ISIS axle; the large tip will hang up on the crank arm of a square-taper crank and probably result in the destruction of the extractor threads in the crank arm. KH/Onza cranks have left-hand threads and can’t be pulled with a standard extractor, Campy used to make a left-handed extractor if you can find one.
Proper use of the extractor is very important. Pull the crank bolts and carefully thread the extractor into the crank. If there is any doubt that you might be cross-threading it, stop. Be sure that you thread it all the way in; a common mistake is to not fully retract the center drive bolt before you start and have the drive bolt contact the axle on the way in. You mistake the feeling of “tight” that comes from the drive bolt blocking the extractor from going in further for “in all the way”. After you thread the extractor in, be sure you can spin the center drive bolt freely with your hands to verify that it isn’t yet touching the axle and that this wasn’t the case. Then you tighten the drive bolt on the extractor until the crank arm releases. If a tapered (square or ISIS) crank has been on for a long-long time, it may be difficult to release. A few quick hops with the bolt out should help loosen it to the point where the extractor will work.
If for some reason you cross-thread the extractor into the crank, or the extractor pulls out of the crank arm (damaging the threads) before the crank pulls off the axle, I’d stop and seek professional help. All is not necessarily lost, but it is best to seek help before doing more damage.
Oh i c how it works, well i ordered this one last night http://www.unicycle.com/shopping/shopexd.asp?id=1230 hope its good. 
i used a med/large sized universal(ish) bearing puller, unscrewed my bolts about 1/2 way and stuck a penny over the end so the puller didn’t mess up the allen threads, and cranked the cranks right off.
i hate my parks tools puller, its such a pain to mess with.